The processing of workpieces for the production of high value products requires accurate measurements of the process parameters for optimization and precise control of the processing steps. The accuracy and reliability of the parameter measurements are critical factors in determining the process capability and product yield.
Descriptions of some of the available technologies and sensor apparatuses for measuring process parameters are available in the technical and patent literature. Examples of some of the technologies are described in U.S. Pat. No. 6,741,945, U.S. Pat. No. 6,738,722, U.S. Pat. No. 6,691,068, U.S. Pat. No. 6,542,835, U.S. Pat. No. 6,244,121, U.S. Pat. No. 6,051,443, U.S. Pat. No. 6,033,922, U.S. Pat. No. 5,989,349, U.S. Pat. No. 5,967,661, and U.S. Pat. No. 5,907,820; all of these patents are incorporated herein, in their entirety, by this reference.
Some of the available technologies use an electronics module that is coupled to the detectors on a support; the sensors and electronics module are part of a single unit that is exposed to the process conditions that are to be measured. The electronics module is necessary for a sensor apparatus with capabilities such as autonomous information processing capability, wireless communication capability, and other electronically controlled on-board capabilities. For some applications, the presence of the electronics module can produce distortions in the parameter measurements.
Of course, the module distortion effect may be ignored if a high degree of measurement accuracy is unnecessary. However, some of the critical process steps required for processing high-value workpieces such as semiconductor wafers for electronic devices and optical devices and substrates for flatpanel display fabrication do indeed require high accuracy for the measurements of the process parameters. For such applications, measurements of a parameter such as temperature need to be extremely accurate, particularly for temperature uniformity across the area of the workpiece. Furthermore, applications involved with the manufacture, calibration, research, and development of process equipment for processing high value substrates require high accuracy measurements since the operation of the equipment can be limited by the accuracy of the measurements. Inaccurate data can result in the loss of millions of dollars of product in some instances. Alternatively, the inaccurate data can result in the production of products having poorer performance because the process conditions were optimized based on the inaccurate data.
There are numerous applications requiring high accuracy methods and apparatuses for obtaining data such as spatially resolved and/or time resolved process parameter measurements with low parameter distortion. An example of an important application is the uniform processing of workpieces such as semiconductor wafers, flatpanel displays, and lithography masks. Furthermore, there is a need for high accuracy methods and apparatus capable of collecting process data in a substantially nonperturbing manner on process equipment running realistic process conditions.